Effect of soil moisture regimes in the early flowering stage on inflorescence morphology and medicinal ingredients of Chrysanthemum morifolium Ramat. Cv. ‘Hangju’

Abstract The quality of the traditional Chinese medicine (TCM) is closely related to the climatic conditions of its medicinal plant’s habitats. When Chrysanthemum morifolium Ramat. cv. ‘Hangju’ (Hj) is in the period of flower-bud differentiation, the rainy season also prevails in its original places. In this study, we set three groups of soil moisture regimes (SMR) corresponding to 35%–40% (S1), 65%–70% (S2), 95%–100% (S3) of soil water holding capacity (WHC) and we found for the first time that the effects of different SMR on the inflorescence of Hj in the early flowering stage. With the increase of SMR content, both ray florets (RFs) and disc florets (DFs) are inhibited on inflorescence morphology, especially for DFs. In addition, a CYC2c orthologous gene in “Zaoyang” (ZY, a cultivar of Hj) was identified and sequenced, the phylogenetic analysis showed that this CYCLOIDEA gene in Asteraceae shared duplications which were well-conserved and lineage-specific. Expression analysis showed that HjCYC2c was mainly expressed in RFs, and high SMR condition led to up-regulation. At the same time, our study suggests that FLS gene is a strong candidate as a key factor in Hj for further interaction studies between flavonoids biosynthesis and regulatory factors of floral symmetry. The determination results of medicinal ingredients showed that DFs were more quickly to respond to the SMR variation and produced more medicinal ingredients compared with RFs.